Shoot 3 scenes of low, average and high contrast and for each of these scenes shoot 3 versions, correctly (or averagely) exposed then one that is one stop darker and another one stop brighter. Resulting in 9 seperate images and histograms to be analysed.
Standard f stop number scale is :-
1.0, 1.4, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45, 64, 90, 128
Each image should then be opened in Photoshop with the highlight and shadow clipping warnings displayed. Screenshots are to be taken along with relevant notation of observations made.
High Contrast Image
The following shots were taken in my back garden on a cloudy day using ISO 400 and a Cloudy WB. The 1 stop gaps between exposures were made by altering the fstops as I am more confident with 1 stop gaps with aperture rather than shutter speed. The correct exposures were taken @ f5.6 the underexposed @ f8 and the over exposed @ f4.
I placed a white statue against a shaded bush hoping this would create enough of a contrast.With a high contrast image the values are spread across the histogram from one end to the other.
Low Contrast Image
With a low contrast image the values are more squeezed together in the histogram. There are no absolute blacks or whites and no clipping was displayed.
Viewing the histogram for the underexposed umage you can see that the values shift to the lefthand side but yet again do not touch the very end of the scale. Once more there are no highlight or shadow clipping warnings.
Average Contrast Image
For an average contrast image the histogram usually the full range of values are represented and the graph gradually peaks in the middle with a gentle slope back down the other side. There was just a minimum of highlight clipping on the pot and a tiny amount of shadow clipping under a few leaves.